U.S. Pat. No. 6,098,288 relates to an electric razor comprising an electromagnetic linear actuator that moves the moving member in a coming and going movement and a second member of the blade type that interacts to cut the hairs. These moving members are magnetised. The European application EP2320543 is also known that describes an actuator comprising a set of permanent magnets magnetised in a direction that is perpendicular to the direction of movement of the movement system, such that the magnetic poles having different polarities alternate on the polar magnetic surfaces of the magnets in the direction of movement, a stator comprising the first and second magnetic poles on both sides of the row of permanent magnets, in a direction that is perpendicular and comprising each one of the magnetic poles facing the magnetic pole surface, a single phase coil exciting the parts of the magnetic poles forming the first and second units of magnetic polar parts.
The international application WO 2000063556 describes an oscillating piston drive, especially designed for an oscillating piston vacuum pump, comprising a housing (2) in which is located a cylinder (3), a piston (4) that can carry out a back and forth movement in the said cylinder, as well as an electromagnetic control component for the piston (4) and comprising an electromagnet (11) on the stator side and at least one permanent magnet on the piston side (18, 19). In order to improve the service life of this oscillating piston drive, permanent magnets (15, 16) are placed on the stator side, and the permanent magnet or magnets (18, 19) are designed and placed such that the piston (4) occupies a substantially central axial position, in the rest state.
U.S. Patent Publication No. 2013/193780 describes an actuator with a fixed part comprising a stator pole a coil fixed to the stator pole, a first moving member that comprises a first magnet magnetised in a direction from the inside towards the outside and placed to cover the external peripheral surface on an extremity in an axial direction from the fixed part, which is mounted elastically on the stator pole, and which is mobile in the axial direction. A second moving part comprises a second magnet that is magnetised in the direction from the interior to the exterior and placed to cover the outer periphery surface of the other end in the axial direction of the fixed part, which is mounted elastically on the stator pole, and which is mobile in the axial direction. When the current flows in the coil, the first moving section and the second moving section move in opposite directions. The coil axis is mounted in a horizontal direction.
The prior solutions have different disadvantages. Most of the proposed structures are mechanically and/or magnetically imbalanced giving rise to vibrations and sound pollution. Furthermore, the moving elements are, in the prior art solutions, combined with magnets that increase the weight and inertia and therefore deteriorate the performances of such actuators.